Osmunda regalis, or royal fern, is deciduous fern, native to North America, Europe, Africa and Asia, growing in woodland bogs and on the banks of streams. The species is sometimes known as flowering fern due to the appearance of its fertile fronds.
The name Osmunda possibly derives from Osmunder, a Saxon name for the god Thor (Wikipedia). The name "royal fern" derives from its being one of our most elegant, largest and more imposing ferns.
Osmunda regalis produces separate fertile and sterile fronds. The sterile fronds are spreading, 60–160 cm (24–63 in) tall and 30–40 cm (12–16 in) broad, bipinnate, with 7-9 pairs of pinnae up to 30 cm (12 in) long, each pinna with 7-13 pairs of pinnules 2.5-6.5 cm long and 1-2 cm broad. The fertile fronds are erect and shorter, 20-50 cm tall, usually with 2-3 pairs of sterile pinnae at the base, and 7-14 pairs of fertile pinnae above bearing the densely clustered sporangia.
An excellent fern for the moist garden, or emersion in shallow ponds, and, as its name implies, it is certainly regal in both size texture, color and habit.
In the eastern United States, this plant is given obligate status as a wetland indicator, which means that it occurs in wetlands, or saturated soils 99% of the time. In many areas, O. regalis has become rare as a result of wetland drainage for agriculture and development.